During the brief Klingon and Romulan alliance during the 2260's, the Klingons acquired cloaking technology from the Romulans in exchange for ship schematics, hulls, and warp
drive. The Klingons also netted several examples of Romulan weapons technologies. The Klingons experimented with fitting these Romulan
weapon systems to their own ships.

In on such example, a light plasma mortar was mounted to a B'rel Bird of Prey in place of its photon torpedo. After combat trials were concluded, the class went into limited
production, resulting in the B'ras class.

The few of these ships suvive into the modern day are used primarily for
punishment duty, the class having fallen out of favour due to its Romulan
weaponry.